Chair backrest



FIG. 1 is a perspective view of a chair backrest showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view of a chair as environmental structure including the chair backrest showing my new design; and,

FIG. 7 is a cross-sectional view of the chair (as environmental structure) of FIG. 6 taken along the section lines 7—7 illustrated in FIG. 4, to provide a bottom view of the chair backrest showing my new design.

The right side elevation view of the chair backrest is a mirror image of the left side elevation view thereof.

All structures shown in broken lines represent environmental structure and are not part of the design sought to be patented. 

The ornamental design for a chair backrest, as shown and described. 